Biomarkers that can detect PD pathology and that can detect disease progression will be most helpful for patient care and proper clinical trial design. As part of the NINDS Parkinson's Disease Biomarkers Program, we seek to collect biological specimens from PD patients and identify serum biomarkers for disease identification and tracking disease progression. PUBLIC HEALTH RELEVANCE: Because the prevalence of Parkinson's disease (PD) is on the rise, it is a public health necessity that the disease be diagnosed at its earliest stage in a relatively non-invasive manner. Biomarkers that can detect PD pathology, and that can detect disease progression would be most helpful for patient care and for proper clinical trial design. The current project seeks to identify serum biomarkers for PD and collect clinical data and new biological specimens from PD patients as part of the NINDS Parkinson's Disease Biomarkers Program.